The goal of this application is to develop and test methodologies for investigating the role of haptic and visual feedback during American Sign Language (ASL) production. Specific aims of the proposed studies are to develop efficient techniques for real-time manipulation of visual information that is available during sign production from the signer's viewpoint; 2) test the efficiency of selective weighting of arm segments that are involved in sign production as a means of manipulating haptic information about their location and orientation in the signing space; and 3) provide an initial data base for identifying sign production parameters that are susceptible to haptic and/or visual feedback alterations. The long-term goals of this research are to expand our understanding of the mechanisms involved in ASL production, in particular in realization of signs' formative aspects, and to put this knowledge to practical service in developing effective communication techniques as well as methods for ASL acquisition. Analyses of sign productions will be both linguistic and motional, and the proposed techniques will permit the independent manipulation of two sources of sensory information generated by sign articulation. This work may allow unique insights into modality- independent characteristics of language production in general.